Patient interfaces, such as a mask assembly, for use with blowers and flow generators in the treatment of sleep disordered breathing (SDB) typically include a soft-patient contacting portion, such as a cushion, and a rigid shell or frame. In use, the patient interface is held in a sealing position by headgear so as to enable a supply of air at positive pressure to be delivered to the patient's airways. When the cushion and frame are manufactured from different materials, they need to be held together in some way. It is also generally desirable that the patient interface be cleanable, for example, allowing a person to wash a mask between uses. While some semi-permanent assembly methods are available, they generally leave small gaps and crevices that can accumulate dirt and be difficult to clean. Hence, it is generally desirable that the frame and cushion include a mechanism that enables both assembly and disassembly. It is also desirable that there be a seal between the frame and cushion to reduce or eliminate leaks from the assembly in use. Since many patients lack dexterity, a good design is simple and easy to use for patients.
A number of cushion to frame assembly mechanisms are known. For example, see U.S. Pat. No. 6,412,487 to Gunaratnam, et al. and U.S. Pat. No. 6,823,869 to Raje et al. Also see ResMed's MIRAGE®, ULTRA MIRAGE®, ACTIVA®, and VISTA® masks.
A problem with existing assembly mechanisms includes difficulty with alignment and assembly, e.g., both putting the cushion onto the frame and putting the cushion clip into the sub-assembly. Another problem with existing assembly mechanisms includes difficulty with adhesive, e.g., gluing, that does not allow disassembly for cleaning. Yet another problem with existing assembly mechanisms includes overmolded parts that can still have points of ingress that cannot be easily cleaned, e.g., see Respironics' ComfortCurve mask. Still another problem with existing assembly mechanisms includes interference methods that can be difficult to use on large frames, e.g. full-face mask, and can have misalignment issues.
Thus, there is a need for an improved assembly mechanism that does not suffer from at least one of the above-mentioned drawbacks.